amount of fuel in fuel filter?


Veteran Member
Sep 5, 2002
1300 km NW of nowhere
The A4 cars are equipped with the thermostat "T" on the fuel line. My understanding is that for fuel temps below a certain temperature, fuel is returned to the filter. For temps above, fuel is returned to the tank.

If this is true, how full should the filter be? If I'm out for a drive and the fuel is above the thermostat temperature, will the fuel filter level drop?

Reason I'm asking: last time I checked my fuel filter it was practically empty. I don't have any bubbles in my clear fuel line, however.

-Dave <== curious